S13 1560mm x 1560mm Double Glazed Polycarbonate Dome without Collar - Clear Description To Fit Existing or Site Formed Curb of 1500mm x 1500mm (External Dimensions) Properties Double Glazed: Light transmission - 77%. Solar heat gain factor - 69%. Sound reduction (db) - 20. Thermal transmission (w/m2k) - 2.68. Features Polycarbonate rooflights comply with HSG 33 (Health and Safety in Roofwork) recommendations. Patented high security screwbolt fixings. Perimeter seal and screw fixing ensure Em-Dome„ rooflight is fully waterproof. All polycarbonate Em-Domes„ use a minimum 3 mm thick glazing. Acrylic Em-Domes„ have a minimum 3mm outer skin. Inner skin thickness varies according to the dome size. When installed in accordance with the manufacturers' recommendations, Em-Domes„ are expected to exceed the life of the roof covering. Em-Domes„ are guaranteed against the effects of defective design, materials or construction for ten years, subject to certain conditions.